Hi,

I've been trying to use the \overrightarrow command within a metapost graphic,
but it doesn't work. Math mode does work, for example \vec works like
expected. Outside of metapost, \overrightarrow works as expected.

To illustrate the problem, I've created the following simple testcase:

  \starttext
  \startMPcode
  draw btex $\vec{foo}$ etex;
  draw btex $\overrightarrow{foo}$ etex;
  \stopMPcode
  \stoptext

This gives the following error output:

  ! Undefined control sequence.
  \dodosmash [#1]->\edef \@@smash 
                                  {#1}\futurelet \nexttoken \dododosmash
  \relbar ->\mathrel {\smash 
                             -}
  \mtharrowfill ...inmuskip \thickmuskip \relax #8#5
                                                    \mkern -#1mu \cleaders
  \hb...
  \dodohandlemathoverarrow ...{\ialign {##\crcr #2#3
                                                    \crcr \noalign {\kern
  #1\n...
  \mathpalette ...>\mathchoice {#1\displaystyle {#2}
                                                    }{#1\textstyle
  {#2}}{#1\sc...
  <argument> ...ex; draw btex $\overrightarrow {foo}
                                                    $ etex;
  ...
  l.5 \stopMPcode

It seems the \overrightarrow command uses \@@smash, which isn't defined when
running from metapost?

Is this expected? Is this a bug?

Gr.

Matthijs